Surveillance and outbreak detection and response

Malaria surveillance is important in every epidemiological setting but it is important to note that it takes different forms.

In areas of very low malaria incidence, where elimination is a realistic goal, programmes will need to identify and respond to every potential malaria case. This entails ensuring that every possible malaria case is accurately diagnosed, and that confirmed malaria cases are treated effectively. Where funds allow, active case detection may also be used. This means taking the tests to the community rather than waiting for symptomatic people to present themselves to a healthcare provider. Active case detection may involve screening whole communities in areas where malaria cases are expected.

In areas of moderate and unpredictable malaria transmission surveillance is particularly important to maintain accurate information on the geographical distribution of the disease. Surveillance of this kind is used to target control efforts and to detect early signs of malaria outbreaks, so that a timely response can be initiated to prevent or limit the size of epidemics. Often such surveillance is conducted through routine reporting of malaria cases identified at health facilities and by peripheral healthcare providers such as village health workers. Efforts need to be made to ensure that this reporting system is accurate and timely. The resulting data needs to be analysed correctly and acted upon swiftly and appropriately.

Upon detection of an outbreak programme managers should conduct an outbreak investigation. This should involve:

A visit to the sites reporting an upsurge in cases,

Investigation of the quality of data and the validity of the reported upsurge in cases,

Mapping the cases and investigating their likely origins,

Focal screening and treatment of any additional cases.

If an outbreak is confirmed the officer responsible should immediately initiate an outbreak response. This should involve:

Entomological assessment and design of vector control response if appropriate. Most commonly any response would involve indoor residual spraying and/or ensuring everyone at risk has access to an insecticide treated bed-net.

Active case detection throughout the target area with expansion of the target area as appropriate if additional cases are identified. This should continue until caseload falls to normal levels.

Communication campaigns to remind communities how to protect themselves and seek treatment,

Continued close monitoring of case reports from the target area and surrounding epidemic prone areas after the outbreak is brought under control.

Malaria surveillance data from all areas is also key to assessing programme impact over time. Where scientific methodology is applied, malaria surveillance data can be used to assess the impact of specific interventions in specific settings, an essential step in the design of locally appropriate malaria control strategies in areas of residual transmission for example.

Routine surveillance is also required at the national level to monitor drug and insecticide resistance. This surveillance enables programmes to ensure that only effective drugs and insecticides are used. In the event of early signs of resistance being detected, prompt action can be taken to avoid treatment or intervention failure and thereby prevent malaria resurgence.